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i' <br /> Wright <br /> Environmental <br /> Services, Inc. <br /> June 15, 2001 Construction ♦ Engineering ♦ Remediation <br /> Project No 4184 1 <br /> City of Tracy - <br /> 520 Tracy Boulevard - = <br /> Tracy, CA 95376 .' <br /> Attn Mr Paul Verma <br /> Re: Addendum Letter 2-Request for Site Closure Report, <br /> Tracy Auto Stereo, 10 West Grant Line Road, Tracy, CA <br /> Wright Project No. 4184; PHS EHD Site Code 504834 <br /> Dear Mr Verma, <br /> Wright Environmental Services has prepared this addendum letter for the above referenced <br /> Site Closure Report for your site A factor was inadvertently dropped from the calculations <br /> for contaminant mass estimates using the Lyman, Reidy and Levy (1992) formulas in our <br /> Site Closure Report dated May 9, 2001 and an inadvertent calculation error was made In <br /> order to provide comparable estimates for all partaes to review, the contaminant mass <br /> estimates have been recalculated using a general formula of contaminant affected soil mass <br /> tunes soil density times average contairunant concentrations, and revised volume for <br /> residual soil The recalculated estimates are presented below and amend earlier submittals <br /> Soil-Contaminant Mass Estimated Removed 1993 <br /> TPHG Concentrations sum of October, 1993 data, 190 cubic yards or 5130 ft3 <br /> Area of 5130 ft3 x average soil density 100 lb/ft3 x 0 002390 ppm = 1226 1 ib <br /> 1225 1 lb — 6 8 lb/gal petroleum product = 180 3 gallons TPHG <br /> Benzene was not detected in that data set. <br /> MTBE was not analyzed for that data set <br /> Soil-Contaminant Mass Estimated Remaining <br /> TPHG <br /> Assumed about 1750 ft3, area of perimeter of excavated area 97 ft x 6 ft wide x 3 ft <br /> capillary fringe height (ringing the excavated area) <br /> Area of 1750 ft3 x average soil density 100 lb/ft3 x 0 000243 ppm=42 5 lb <br /> 42 5 —6 8 lb/gal petroleum product = 6 25 gallons TPHG <br /> Benzene <br /> Area of 1750 ft3 x average soil density 100 lb/ft3 x 0 000003134 ppb = 0 54 lb <br /> 0 54 lb -f- 6 8 lb/gal petroleum product = 0 0$ gallons Benzene <br /> MTBE was not detected in that data set. <br /> The calculations for water were recalculated as a unit error was made, and the following <br /> estimates resulted <br /> 67 E 10th Street o Tracy,CA 95376 j <br /> 209 833 0758 ♦ Fax 209 832 5152 <br /> wrtght@tnreach com Ltc #651501 A-B HazMat Page 1 ice, <br /> webstt http//home:nreach comhvright <br />